Chapter 10 NAT
LTE5366 Series User’s Guide
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10.5 ALG Screen
Some NAT routers may include a SIP Application Layer Gateway (ALG). A SIP ALG allows SIP calls to pass
through NAT by examining and translating IP addresses embedded in the data stream. When the
LTE5366 registers with the SIP register server, the SIP ALG translates the LTE5366’s private IP address inside
the SIP data stream to a public IP address. You do not need to use STUN or an outbound proxy if your
LTE5366 is behind a SIP ALG
To enable and disable the SIP ALG in the LTE5366, click
Configuration >
Network > NAT > ALG
. The screen
appears as shown.
Figure 62
Configuration > Network > NAT > ALG
The following table describes the labels in this screen.
10.6 Technical Reference
The following section contains additional technical information about the LTE5366 features described in
this chapter.
10.6.1 NAT Port Forwarding: Services and Port Numbers
A port forwarding set is a list of inside (behind NAT on the LAN) servers, for example, web or FTP, that you
can make accessible to the outside world even though NAT makes your whole inside network appear
as a single machine to the outside world.
Use the
Port Forwarding
screen to forward incoming service requests to the server(s) on your local
network. You may enter a single port number or a range of port numbers to be forwarded, and the local
IP address of the desired server. The port number identifies a service; for example, web service is on port
80 and FTP on port 21. In some cases, such as for unknown services or where one server can support
Table 41 Configuration > Network > NAT > ALG
LABEL
DESCRIPTION
ALG-SIP
Select
Enable
to make sure SIP (VoIP) works correctly with port-forwarding and address-
mapping rules. Otherwise, select
Disable
to turn off the SIP ALG.
Apply
Click
Apply
to save your changes back to the LTE5366.
Cancel
Click
Cancel
to begin configuring this screen afresh.
